physics EM
posted by Spencer .
using the Amperes Law
The circle on the integral means that B(r) must be integrated
A. over a circle or a sphere.
B. along any closed line that you choose.
C. along the path of a closed physical conductor.
D.over the surface bounded by the currentcarrying wire.
Im pretty sure its B but I just wanna be positive thank you.

oops theres a D too.
D. over the surface bounded by the currentcarrying wire. 
i need to know the forms of basic crystals

http://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_law
"closed Path" which encloses current. B is the best answer. If you choose a closed path which encloses no current, then B is zero. On answer B, it would have been much better to word it "along any closed path that you choose". The word line, technically, cannot form a closed surface, and so the term "closed line"is somewhat without meaning. 
I know its this stupid Mastering Physics site. It can word things that straightforward.
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